Localization of chromophore absorption signals in TEM with an improved prism-mirror-prism filter
| Autor: | Yew Meng Heng, Jason A. Davis, Melanie M. G. Barfels, Jean Gariépy, F. Peter Ottensmeyer, Stuart K. Bisland |
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| Rok vydání: | 2000 |
| Předmět: |
Radiation-Sensitizing Agents
Microscope Porphyrins Context (language use) Molecular physics law.invention Cell Line Mice Optics law Electron beam processing Animals Absorption (electromagnetic radiation) Instrumentation Image resolution Cytoskeleton Fluorescent Dyes Chlorophyllides business.industry Chemistry Resolution (electron density) Chromophore Fibroblasts Phenylmercury Compounds Microscopy Electron Hemin Prism business Crystallization Fluorescein-5-isothiocyanate |
| Zdroj: | Journal of electron microscopy. 49(5) |
| ISSN: | 0022-0744 |
| Popis: | A corrected prism-mirror-prism electron energy filter with curved entrance and exit faces was designed and incorporated into a Zeiss EM902 transmission electron microscope. The installation of the new filter required little modification to the existing microscope geometry and electronics. The filter had an energy resolution of 1.1 eV over the full image plane (acceptance half angle 10 mradian). The improved energy resolution was applied in studies of the low electron energy loss region that includes molecular orbital excitations or chromophore energy absorptions. Chromophore signal behaviour under electron irradiation was characterized using embedded crystals of hematin and of the dye mercury orange. Images of these crystals confirmed the expected decrease in signal intensity on shifting the selected energy loss from the region of molecular orbital excitations (less than approximately 5 eV) to higher energy losses. Electron irradiation-induced fading of the chromophore signal from hematin and mercury orange yielded similar 1/e dose values of 1.1 x 10(5) e(-) nm(-2) and 1.4 x 10(5) e(-) nm(-2) respectively. In a cellular context, chromophore signals were obtained from energy-filtered images of RIF-1 cell sections containing the photosensitizer chlorin e6 and from sections of BS-C-1 cells with cytoskeletal labelling via FITC-conjugated antibodies. The respective signals were extracted using a dose-dependent method or a shift in selected energy. Chromophore signal distributions were in agreement with fluorescence light microscopic images, but provided detail at higher spatial resolution. |
| Databáze: | OpenAIRE |
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